Cases or housings that allow conventional mechanical still or movie cameras to be used under water have been popular for many years and the details of their construction are the subject of numerous patents. Interest in similar cases for videotape and digital cameras has increased in recent years as this equipment has become less expensive and has incorporated more desirable features. Although cameras designed specifically for use under water (incorporating a waterproof case) have been manufactured, it is sometimes judged less expensive to adapt a mass-produced conventional camera for underwater use. Often, the methods used to operate a camera incorporating a case designed specifically for underwater use are similar to those used in after-market underwater cases or housings. In practice, the methods used for operating various controls on cameras incorporating waterproof cases as well as cases intended for adapting conventional cameras for underwater use have been observed to have shortcomings.
Some schemes for operating the controls of underwater cameras have used one or more O-ring seals that allow a metal or plastic rod to physically turn or slide and operate the camera control(s). These O-rings require regular maintenance and have frequently been observed to allow water to enter the case as a result of wear, contamination or flattening of the rubber. The likelihood of a leak increases with the number of O-rings in the case. As may be imagined, even a small amount of water is undesirable for photographic or electronic equipment.
Magnetic coupling through a waterproof case to a reed switch (or other magnetic sensing device) inside allows operation of the camera (or other equipment) controls without the need for a sliding or rotating seal and the associated risk of a leak. Generally, the operator displaces a permanent magnet movably mounted outside the waterproof case. When moved into close proximity, the field from the magnet closes the contacts of the reed switch (or activates some other magnetic sensing device) located inside the waterproof case. The reed switch (or other device) completes a circuit in the camera or operates an electric motor to accomplish the desired function. Additional complexity and expense are associated with these controls since a motor, gearing and power supply must be supplied or else the appropriate circuit in the camera must be interrupted and electrical connections installed and wiring provided to the reed switch (or other sensor) to complete the circuit.
Rotational magnetic couplings have allowed a knob turned outside the waterproof housing to rotate a control on a camera inside. Two circular arrangements of permanent magnets, one inside and one outside, transmit the rotational motion. Focus, exposure adjustment and film advancement may be accomplished on older-style cameras. Sometimes gears are incorporated to change the number of turns or amount of torque required to operate the control. This method eliminates the risk of leak associated with an O-ring but is limited in the functions it can provide.
The use of cases that are thin enough to be flexible (resembling a bag) or rigid cases which incorporate flexible parts or areas allow the mechanical operation of the camera controls within. In their simplest embodiments, the maximum depth to which these cases are useful is limited by the hydrostatic pressure exerted on the camera or the controls themselves (a shutter button continuously depressed by water pressure is an example). Mechanical solutions to this problem have been patented and incorporate internal pressurization of the case, more complicated mold designs, additional molding steps, cantilever beams and/or additional mechanical components. These solutions generally add expense and complexity and limit the minimum size of any controls, which can be operated.
It is an object of the present invention to provide a simpler, less expensive and more reliable method for operating the controls of an underwater camera. It is a further object of the present invention to provide an actuator that is small enough to use with the more numerous and smaller push button controls that are now common on various electronic cameras. It is a further object of the present invention to provide a means of mechanically operating the controls on cameras in underwater cases thus making electrical connection unnecessary. It is a further object of the present invention to provide a method for operating popular controls other than push buttons including “rockers” as well as two-axis or three-axis “control buttons”. It is a further object of this invention to provide a means for operating the controls of a camera designed specifically for underwater use (Incorporating a waterproof case) in addition to a camera contained in a case or housing intended to adapt it for underwater use. Still further objects and advantages will become apparent from a consideration of the ensuing description and accompanying drawings.